Presentation on theme: "Site Conceptual Models"— Presentation transcript:
1Site Conceptual Models Keith KezerSAM Project ManagerGeneral introduction of myself.Laidlaw Environmental – Field Chemist1. Package and transport hazardous materials2. Remedial activities including excavationTRC – Staff level to Senior Management Level1. Started as entry level field grunt (field work, research, report preparation)2. Managed intricate programs for a couple major oil companiesCounty of San Diego – Project Manager1. Previous experience as a consultant helped enormously
2Why a discussion on SCMs? Confusion on exactly what a SCM isClarify the goals of a SCMProvide guidance on when a SCM is necessaryHave consistency on the contents of SCMsProvide opportunity to address consultant questions and provide clarifications.The confusion about SCMs is evident in discussions with multiple consultants and review of reports.
3How many think this a SCM? There are some good ideas in this figure related to exposure concerns but we’ll have to see in terms of a site conceptual model
4SCM questions received by DEH Why do we need to submit boring logs and cross sections?Why do we need to re-submit information that was already submitted to DEH?Why must a receptor pathway evaluation be included in a site assessment report?For those of you who question the necessity of a SCM discussion I have a couple of questions we have received repeatedly at the DEH. I’d like to take just a minute or two to briefly discuss their importance.Boring logs and Cross Sectionsa. To better understand the relationship of underground structures (utilities, water ways) and geology to contaminant locations and how and why contaminants are migrating (i.e. through sand layers, on clay layers etc.)2. Information Re-submittala. The typical DEH project manager has approximately 100 cases that they manage. If the information is not provided with each report DEH staff would have to memorize it or spend countless hours reviewing files.b. The typical case has 5 to 15 folders of information, many of them 20 to 30 folders which is lot of information to sort through to find a simple fact like whether or not a site passed a benzene vapor risk assessment.c. A site conceptual model is comprehensive in nature.3. A receptor pathway evaluationa. DEH uses a risk based cleanup approach, risk is defined as receptors and the potential for them to be impacted.b. Conditions may change even if assessment activities are complete (i.e. groundwater elevation increases)c. A receptor pathway evaluation must be updated as assessment continues at the site.
5SCM Definition Keith Kezer Definition: A comprehensive compilation of data, interpretations, and site specific circumstances which describe and explain the environmental conditions of a site based on all available information.Generally speaking:A SCM is a SAR and as a result this presentation is based on and build around the site SAM Site Assessment Report Checklist which includes the majority of the contents for a SCM.
6Goals of an SCMProvide a clear understanding of the existing environmental site conditions based on accessible/available informationMinimize or eliminate erroneous activitiesBased on the SCM provide a clear recommendation to move to closureUtilize existing regulatory framework as a guide to closure (MCLs/Low Risk Sites)With the previous definition in mind, what are the goals of a SCM.1. Utilize previous SCMs to ensure wells are installed appropriately and remediation alternatives are viable.2. Provide and interpret all applicable dataa. Use example of site with multiple wells screened below GW after initial assessment determined DTW.3. What should be done next to move the case to closure. Remember that DEH is not managing the case, we are participating in a guidance role not a management role.4. Use regulatory framework to guide the case to closure including MCLs, RWQCB has a document for the management of low risk sites, etc.
7When is a SCM necessary?Whenever assessment activities are conducted for a site.If site circumstances or conditions have changed or data is outdatedAs part of a health risk assessment or a receptor pathway evaluationAs part of any corrective action plan or closure document.Not groundwater monitoring reports since these activities only provide a very limited amount of data as an update.If a site has been inactive for a number of years or other major site changes (i.e. depth to GW change that is significant).Essentially to better understand the relationship between contaminants and receptors (i.e. benzene plume vs. building location).To understand the relationship between contaminants and the proposed remedial strategy.
8General SCM Characteristics Every site will include different information depending on its specific circumstancesContains in depth analysis and successful presentation of dataComprehensive in nature including all historical data and pertinent eventsIncludes a clear objective and direction for the site substantiated by the SCM contentsEvery site is differentDepth to water (or estimate)Extent of known or suspected contaminationNearby land use / characteristics / ReceptorsPresentation and analysis1. Legible/useful figures2. Applicable tables with pertinent information (comprehensive)3. Rational behind decisions/interpretationsComprehensiveComprehensive tables and figures comprehensive (not just copies of previous consultants work unless you can trust and agree with it and a narrative is included to explain it.)Include previous applicable information like a benzene vapor risk evaluation or excavationOnly pertinent information should be includedEach subsequent assessment should build on the previous assessment (i.e. data from all past assessments must be included)Clear objective and direction1. What needs to be done next?? Based on your professional experience and the existing SCM are there data gaps that need to be addressed?
9SCM Summary General Site Characteristics History, Business type, Surrounding land use, RPs, Location, Geology, Hydrogeology, Receptors, Contaminant(s) etc.Procedure and Contaminant InformationRelease description, Sampling information, Soil, vapor and groundwater data interpretation (Figures)DiscussionRisk discussion (including receptor pathway evaluation), Substantiate interpretations, provide backupConclusions and RecommendationsTrends, Risk and Delineation conclusions, data gaps, and recommendations on what to do next.Keep in mind that DEH uses a risk based closure scheme pursuant to the Fund Contract.General Site Characteristics1. Playing Field – There’s a lot of information here!!2. Goals or objective of assessmentProcedure and Contaminant InformationAssessment procedures (both general and specific)Contaminant data and interpretations (figures and interpretations)DiscussionHas any new risk been identified or can previously identified risk be discounted based on new informationData trends, graphs, etc.Interpretation substantiation and backup for Conclusions and RecommendationsConclusions and RecommendationsTrends based on discussion and interpretationsRisk – what requires additional evaluationData GapsWhat do we do next
10SCM Contents Site Identification a. Site address (street name and number, city, state, zip code)b. Name of business at sitec. Assessor's Parcel Number (APN)d. DEH Case Number (e.g., H )e. Property owner (name and mailing addressf. Tank owner (name and mailing address)g. Tank operator (name and mailing address)h. Contact person (name, mailing address and phone number)i. Responsible party (name and mailing address)j. Location mapsWhy do these things need to be in every report?To ensure that all involved are on the same page.Information can be lost with DEH staff change, RP change, consultant changes etc.DEH must be notified when the property changes hands per regulations.
11SCM Contents Site History/Development/Usage a. Historical site use (including potential sources of contamination and dates)b. Current site use (including potential sources of contamination and dates)c. Future site use and development plans (type of use, new construction, below-grade structures, proposed excavation work, elevator shafts, vaults, utility trenches)d. Adjacent site uses (Site Vicinity Map)Do not include a chronology of everything that’s ever happened at the site.Keep it applicable and up to date. Adjacent site uses are changing rapidly in this real-estate market.
12SCM Contents Description of Release and Site Plot Plan a. Substance(s) releasedb. Contaminant characterizationc. Quantity of substance(s) released (estimate)d. How and when release occurrede. Location of release on site (can be based on data)f. Drawn to scale (indicate scale used)g. North direction arrowh. Streets, structures, and utilitiesi. Excavation and stockpile locationsj. Tank and piping locations (past, existing, proposed)k. Well, boring, and sample locationsl. Legend for symbols and abbreviationsThis information should always be provided WHEN APPLICABLE.Suspected location of release (can be based on contaminant data)
13Site Plan Showing Utilities and Depths Standard site plan informationGeneral site layout with surrounding streets and namesNorth arrowScaleOnsite structures and buildingsUSTs, dispensers, and pipingUtilities with depths (if applicable)Other pertinent information including surface contours fences etc.
14SCM Contents Geology, Hydrology and Hydrogeology a. Local geology descriptionb. Site geology description (based on borings)c. Topographyd. Surface drainage and surface-water bodies in vicinitye. RWQCB basin plan hydrographic unit, subunit identification, and aquifer sensitivity status.f. Groundwater elevation measurements and depth to groundwaterg. Groundwater gradient and direction of groundwater flowh. Description of all groundwater aquifersi. Known or probable contaminant migration patterns (consider hydrogeology, groundwater gradient, utility trenches, etc.)j. Source of informationa. Differentiate between local geology and site geology (indication of fill vs. native)h. Alluvial or fracture flow
15SCM Contents Delineation of Contamination (Soil) a. Summary table(s) of analytical data with sample identification, date, depth, location, analysis method(s), results, etc.b. Map(s) showing horizontal extent of soil contamination, probable contamination sources, contaminant migration pathways, well and boring locations, sample locations, and sample resultsc. Cross sections showing vertical and horizontal extent of soil contamination, contamination source(s), lithology, water table, sample locations, sample results, and underground structuresf. Estimated mass/volume of contaminated soil (when applicable)Make sure you include a narrative in addition to the figures to explainWhat the figures depictExceptions, special circumstances, or noteworthy informationGeneral discussions or conclusions based on data and figures.
16Soil Concentration and Contour Map Example Important items to include on a map view concentration map1. Concentrations of CoC’s with depths (in this case the samples were differentiated by color for UST removal samples versus borings)2. Cross section lines3. Contaminant contour line with explanation.
17Cross Section Example Figure Important items to include on a cross sectionDepth and elevationUST pitUnderground UtilitiesLaboratory analytical dataMeasured groundwater rangeScaleLiquid-Phase HydrocarbonsContoured soil contamination that matches the plan view figure.
18SCM Contents Delineation of Contamination (Groundwater) a. Summary table(s) of analytical data with sample identification, depth, location, analysis method(s) and resultsb. Map(s) showing horizontal extent of groundwater contamination, well locations, sample results, product thickness in wells, groundwater elevation in wells, groundwater elevation contours, and groundwater flow directionsc. Environmental parameters or manmade features which may affect the spread of contaminationC. Examples of Environmental parameters or manmade features1. Utilities, footings, or other subsurface structures2. Lithology (clay layers, competent rock, etc.)
19Groundwater Contaminant Contour Map Example Important items to include on groundwater contour mapsWells with identificationWell concentrationLPH contourCoC contours (usually logarithmically distributed)Contour line labelsDate of sampling
20SCM Contents Exposure Concerns a. Contaminant migration pathways description and receptor pathway evaluationb. Man-made pathways (conduits, utilities, vaults, piping, storm drains, etc.)c. Natural pathways (air, soil, surface water, bedrock fractures, groundwater, etc.)d. Impact on biological receptors (people, plants, animals)e. Potential nuisance complaints (odors, eyesore)f. Risk assessment concepts and calculationsg. Identify all production and potable water supply wells within feet of the site by means of area site visit, California Department of Water Resources (DWR) records, etc.A receptor pathway evaluation must identifyEach receptor (what are we protecting)Contaminants of concern (what are we protecting it from)Each pathway (how will the CoC get from point A to point B.)Quantitative analysis of potential risk with all backup and calculations
21SCM Contents Sampling a. Protocol description b. Methods c. Preservation and transportd. Analyses performede. Chain-of-custody formsf. Sample matrix description (clay, sand, water)g. Laboratory analytical reports (on letterhead)h. Quality assurance/quality control datai. Interpretation of analytical results with respect to previous and current understanding of the sitea. Sampling protocol ensures that DEH understanding how the sampling was conducted and provides guidance and consistency to field staff.
22SCM Contents Stockpiled Soil Management and Site Safety a. Volume b. Locationc. Methods used to prevent aeration, run-off and public accessd. Disposal methodse. Copies of manifestsf. Site safety/security descriptiong. Community health and safety issues addressedh. Monitoring equipmenti. Protective equipmentj. Public agency notificationsk. Utility notifications (Call USA 48 hours before work by law)Only if applicable.
23SCM Contents Conclusions, Recommendations, Signature a. Horizontal and vertical extent of soil and groundwater contamination explanationb. Additional assessment or other recommendationsc. Alternative mitigation recommendationsd. Signature(s) of report preparer(s)e. Signature(s) and registration number(s) of the registered professional(s) who supervised and is responsible for designated portions of the reportf. Authorized signature for the company preparing the report (original signatures required--no draft, unsigned, or electronically signed reports)
24SCM Contents Appendices a. Well/boring logs b. Hazardous waste manifests and disposal receiptsc. Permits (APCD, Fire Department, Wells, etc.)d. Laboratory data sheetse. Chain-of-custody formsf. Backup information including calculations, notes, photographs, etc. as applicableFor all wells and borings installed as part of this assessment. Other applicable boring logs may be necessary as well.
26Closing CommentsMost of the information above will not need to be recreated each time a SCM is submitted and therefore shouldn’t require excessive effort to incorporate into future documents.If this information is included in every SCM there’s less chance of information being lost etc.The number one reason DEH receives for an incomplete SCM is that the information is not available (which usually means not easily available)That was a lot of information, howeverIf site conceptual models are complete:Cases will be turned around more quicklyCases will be managed more efficientlyDecrease the work load of all involved.Move the case to closure more quickly while protecting public health.